Building block toy



FIG. 1 is a top perspective view;

FIG. 2 is a bottom perspective view;

FIG. 3 is a top and side perspective view;

FIG. 4 is a bottom and side perspective view;

FIG. 5 is a top view; and,

FIG. 6 is a bottom view.

The broken lines shown in the figures form no part of the claimed design. 

CLAIM The ornamental design for a building block toy, as shown and described. 